A light emitting diode (LED), a type of semiconductor light emitting device, is a semiconductor device capable of generating light of various colors according to the recombination of electrons and holes at p and n type semiconductor junctions when current is applied thereto. Compared with a filament-based light emitting device, the semiconductor light emitting device has various advantages such as a longer lifespan, lower power consumption, excellent initial driving characteristics, high vibration resistance, and the like. These advantages make demand for the semiconductor light emitting device continue to grow. In particular, recently, a group III-nitride semiconductor capable of emitting short-wavelength blue light has come to prominence.
A light source module used for an LCD backlight, or the like, conventionally employs a cold cathode fluorescent lamp (CCFL). Use of mercury gas, however, incurs disadvantages in that it has a slow response speed and low color reproducibility (or a color gamut) and is not suitable for a light, thin, short, and small LCD panel. In comparison, an LED is environmentally-friendly, has a fast response speed, within the range of a few nano-seconds, to provide a high speed response, and is thus effective for a video signal stream, is available for impulsive driving, has a color gamut of 100% or higher, can arbitrarily change luminance, color temperature, or the like, by adjusting the quantity of light emitted by red, green and blue LEDs, and is suitable for a light, thin, short, and small LCD panel. As such, the LED has been actively employed as a light source module of a backlight.
As an expansive employment of a light emitting diode as a light emitting module for a backlight, a need exists for a method for enhancing uniformity of emitted light.